I thought about filling it about half way with rocks, then adding soil, and having a "sunken" yard.

Luck was with me, I met him at the Gym. a couple months Later, I did reserch for him for foreclosure properties, the best property I found him was a 3 unit with a bar underneath, He sold it a couple months later for a very good profit, He gave me 10 grand for the work.

It also had a Victorias' Secret- I guess underneath the robes the women are the same around the World!

Coastal soils all vary in composition, and cities/counties requirements for stabilizing those soils are all different.

Oil prices dropped in half in the year 1986 alone, along with a 6-year price drop due to the 80's oil crisis.

As far as the tree, it depends on how close it is to the house and what kind of soil you have.

If it is in the walls and we know what it may be (tobacco, pet, etc), we have a recipe (tsp, rinse, seal, paint)... or if it is from the floors, we clean or even pull the flooring (seal underneath refloor, etc)...One simple carpet one I use is sprinkling the large (13.5 lb)  bags of baking soda into the carpet (if carpeted)... work it into the floor with stiff broom, so it gets into carpet to pad.

@Daniel Moctezuma, I don't have any direct experience but the problem that I see is if the tank leaked you may have an environmental clean up on your hands (need to clean up the soil as well) - it may not be as "simple" as only removing the tank. 

I am unsure of the legality of this but I've heard it done successfully by others.Keep turning over rocks until you find something exciting underneath. 

Is you need to put money aside for foundation issues its not if Its when.. everyone of my homes I had we had some sort of work to do to address shifting soils..